1. Technical Field
The present invention relates to an illumination device.
2. Related Art
It is known that an organic EL (Electro-Luminescence) material used for light emitting elements of an organic EL panel which is an example of an illumination device has a problem that the luminance of emitted light varies, depending on the ambient temperature, due to temperature characteristics unique to the material. Because of the unique temperature characteristics of the material, particularly, an illumination device suffers a considerable reduction in display quality or “uneven luminance”. The “uneven luminance” mentioned herein is originated from a change (deviation) in the I-L characteristics (current-optical output characteristics) that is caused by a temperature difference which may occur in the surface of the substrate (particularly, near the center of the substrate and near the periphery thereof).
JP-A-2007-234447, for example, discloses the technique of detecting the temperatures of a plurality of portions by means of a temperature detector to thereby detect the temperature of the luminescent section so that high-quality image display without uneven luminance is achieved. Further, JP-A-2008-181008, for example, discloses the technique of using a plurality of portions in the luminescent section as light emitting portions and also using the portions as portions whose temperatures are to be detected to thereby accurately detect the drive temperature of the luminance element.
JP-A-2007-234447 discloses the temperature detector provided on an opposing substrate, however, a method of detecting the temperature is not specifically described therein. JP-A-2008-181008 discloses the technique using wires and switches for detecting the temperature, resulting in a higher cost.